<?php

namespace Mageplaza\HelloWorld\Plugin;

class Product
{
    protected $_logger;
    public function __construct(\Psr\Log\LoggerInterface $logger)
    {
        $this->_logger = $logger;
    }

    public function  afterGetPrice(\Magento\Catalog\Model\Product $subject, $result)
    {
        $this->_logger->info("Product",['before'=>$result]);
        return $result+100;
    }
}